Poison

Poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism. In medicine (particularly veterinary) and in zoology, a poison is often distinguished from a toxin and a venom. Toxins are poisons produced via some biological function in nature, and venoms are usually defined as biological toxins that are injected by a bite or sting to cause their effect, while other poisons are generally defined as substances which are absorbed through epithelial linings such as the skin or gut.

Let me have
A dram of poison, such soon-speeding gear
As will disperse itself through all the veins
That the life-weary taker may fall dead
And that the trunk may be discharg'd of breath
As violently as hasty powder fir'd
Doth hurry from the fatal cannon's womb.

All men carry about them that which is poyson to serpents: for if it be true that is reported, they will no better abide the touching with man's spittle than scalding water cast upon them: but if it happen to light within their chawes or mouth, especially if it come from a man that is fasting, it is present death.